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SubjectRe: mmap() versus read()
Date
> 
> On Mon, 9 Mar 1998, Larry McVoy wrote:
>
> > The real problem is this: can a process put a request in the disk
> > queue and then return from system all, leaving the OS to finish it up?
>
> It could if we use a kernel thread to do the actual paging...

Hmm, genuine bonified Kernel Threads(tm) are looking more tantalizing
aren't they? Actually I think Sloaris' use of kernel threads is an offense
punishable by death. I do, however think that the lwp/thread model is
useful. Mainly because if you thread certain system/libc calls, a
non-mt program can benefit from an MP machine. I think everyone will
agree that the current clone() method of creating threads is costly
at best. I think that an LWP implementation would be tremendously
useful. Solaris doesn't really have threads in the kernel (AFAIK),
but rather implements LWPs, upon which the core of the libthread is
implemented as an abstract layer. Having LWPs in Linux could prove
very useful. I think that the concept of "process" in Linux would
have to change to be a "container", rather than a schedulable entity.
LWPs are the actual schedulable entites in Solaris, a process may
contain many LWPs which are scheduled and billed to that process.
At the simplest level, processes are an LWP with a single thread
running on top, executing main(). Working on a Solaris machine
all day (read programming), I have to say that Linux is inferior
with regards to threads. I would love to see Linux be superior to
Solaris in every aspect, threads is a fairly rudimentary requirement.

FWIW,

--Perry


>
> Rik.
> +-----------------------------+------------------------------+
> | For Linux mm-patches, go to | "I'm busy managing memory.." |
> | my homepage (via LinuxHQ). | H.H.vanRiel@fys.ruu.nl |
> | ...submissions welcome... | http://www.fys.ruu.nl/~riel/ |
> +-----------------------------+------------------------------+
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--
Perry Harrington Linux rules all OSes. APSoft ()
email: perry@apsoft.com Think Blue. /\

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